Airbag module

ABSTRACT

The invention relates to an airbag module for motor vehicles, comprising an inflatable airbag ( 12 ) and a deflection pocket which is arranged in the region of an inflow opening of the airbag and which consists of at least two material layers, of which a lower layer ( 16   a ) has a flow-through opening ( 18 ) which is aligned with the inflow opening and is at least partly covered over by an upper layer ( 16   b ), and is secured at a holder element ( 22 ) for the airbag, with the upper layer being connected region-wise to the lower layer for forming radial gas propagation paths ( 24 ) for gas flowing via the deflection pocket into the airbag.

TECHNICAL FIELD

The invention relates to an airbag module for motor vehicles, comprisingan inflatable airbag.

BACKGROUND OF THE INVENTION

In airbag modules of this kind the airbag should deploy as rapidly aspossible in the event of an accident in order to protect the vehiclepassenger in the inflated state.

The problem (object) of the invention is to create a possibility ofoptimally protecting vehicle passengers by means of an airbag which canbe inflated in the event of an accident, with it being desirable inparticular for an optimal protection to be given even when the relevantvehicle passenger does not assume his normal seated position.

SUMMARY OF THE INVENTION

This object is satisfied by an airbag module that includes a deflectionpocket which is arranged in the region of an inflow opening of theairbag and which consists of at least two material layers lying oneabove the other, of which a lower layer has a flow-through opening whichis aligned with the inflow opening and is at least partly covered overby an upper layer, and is secured to a holder element for the airbag,with the upper layer being connected region-wise to the lower layer forforming approximately radial gas propagation paths for gas which flowsvia the deflection pocket into the airbag.

The deflection pocket in accordance with the invention ensures that gaswhich is expelled by a gas generator does not flow directly into theairbag, but into the deflection pocket first. After the gas has passedthe flow-through opening of the lower layer of the deflection pocket, itencounters the upper layer, which at least partly covers over theflow-through opening. Since the upper layer is connected to the lowerlayer and the lower layer is in turn secured to the holder element ofthe airbag module, the deflection pocket can not move in the axialinflation direction towards a vehicle passenger, but rather the gas isdeflected in such a manner by the upper layer that it flows along theradial gas propagation paths of the deflection pocket, which extendperpendicular to the axial inflation direction, and emerges from thedeflection pocket in the radial direction and enters into the airbag.

In the airbag module in accordance with the invention the airbag is thusfirst inflated in the radial direction; i.e. through the invention aninitial radial deploying of the airbag is achieved. The deflectionpocket which is formed by the material layers which are connectedregion-wise to one another thus ensures in accordance with the inventionthat during the inflation of the airbag an impact surface with largeradial dimensions is first created before the airbag can deploy axiallyin the direction of a vehicle passenger. The airbag can thus not deploypast the vehicle passenger during the inflation or thrust the vehiclepassenger against the inner wall of the vehicle. Inflation inducedinjuries—IIIs—are consequently prevented through the invention.

The gas propagation paths can be configured in dependence on therespective conditions in such a manner that the gas flows into theairbag distributed in the desired way over the periphery of thedeflection pocket. In this the deflection pocket in accordance with theinvention thus has not only a deflector function for deflecting the gasflow, but also a diffuser function for the optimal distribution of thegas in the airbag.

The material layers can be manufactured of a flexible material, e.g.textile or fabric material, so that they form a flexible deflectionpocket by means of which the gas flow can be deflected and distributedin the respective desired way.

An advantage of a flexible deflection pocket consists in that the lattercan reach up to possibly present lateral side walls of a cover or cap ofthe airbag module or, respectively, extend over side walls of this kind.Through this the gas flow can be deflected into a direction which is notdangerous for the relevant vehicle passenger.

A further advantage of the invention is that the radial deployment isrealized in a particularly simple and efficient way in that merely thedeflection pocket, which is formed of the material layers which lie oneabove the other, is provided. Complicated structures within the airbagsuch as for example inner walls, layers or lobes, which extend throughthe entire airbag, and elaborate measures for connecting structures ofthis kind to the actual airbag sheath are in accordance with theinvention not required. Likewise, complicated tethers or holder bandarrangements within the airbag can be dispensed with. The weight of theairbag module and its manufacturing costs are practically not increasedthrough the deflection pocket in accordance with the invention.

A further advantage of the invention consists in that the materiallayers which form the deflection pocket protect the airbag from the heatwhich arises during the triggering of the gas generator.

Whereas it is possible in principle that the two material layers areformed by a single connected sheet of material, it is preferred when thedeflection pocket is formed not by a single e.g. sleeve-like or bag-likepiece of material, but rather by at least two separate material layers.

In a preferred practical embodiment of the invention the lower layer isformed of a material layer which is provided as a heat shield for theairbag. In this a constituent of the airbag module which is presentanyway is used for forming the deflection pocket in accordance with theinvention. The weight and manufacturing costs of the airbag module inaccordance with the invention are reduced still further through this.This execution has a particularly advantageous effect on the manufactureof the airbag module since it is merely necessary to apply an additionalmaterial layer to the material layer which forms the heat shield. Thusan additional deflector or diffuser function respectively can hereby beimparted to the heat shield of the airbag module, with the additionalupper layer at the same time increasing the heat protection function ofthe lower layer.

In a further exemplary embodiment of the invention the holder element isdesigned in the shape of a ring, with both the inflow opening of theairbag and the flow-through opening of the lower layer being bounded bythe holder element. With a holder element of this kind it is for examplepossible to secure both the airbag and the lower layer of the deflectionpocket, e.g. through clamping in at the airbag module, in such a mannerthat the relative position of the airbag and the deflection pocket isreliably fixed and the inflow opening of the airbag and the flow-throughopening of the deflection pocket are aligned with one another so thatgas which is produced by a gas generator can flow via the inflow openingof the airbag and the flow-through opening of the lower layer into thedeflection pocket.

It is particularly preferred when the lower layer and the upper layerare connected to one another at least at one line-shaped or strip-shapedconnection location, with the connection location being formed by atleast one seam. To form strip-shaped connection locations, double seamscan also be provided. The material layers, which can for example consistof textile or fabric material, are thus simply sewn to one another toform the deflection pocket.

In principle the material layers which form the deflection pocket can beconnected to one another in any desired manner, for example throughadhesive bonding or welding.

The invention also relates to a method for manufacturing an airbagmodule for motor vehicles, in which at least one further material layeris applied in such a manner to at least one present material layer whichis provided as a heat shield for the airbag that a deflection pocketwith approximately radial gas propagation paths for gas which flows viathe deflection pocket into the airbag is formed by the material layers.

Furthermore, the invention relates to the use of at least one materiallayer, which is provided as a heat shield for an airbag in an airbagmodule, as one of at least two material layers through which adeflection pocket is formed with approximately radial gas propagationpaths for gas which flows via the deflection pocket into the airbag.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, withreference to the accompanying drawings, in which

FIG. 1 is a schematically indicated airbag, a deflection pocket of apartly illustrated airbag module in accordance with an embodiment of theinvention, and

FIG. 2 is an illustration in accordance with FIG. 1 with a deflectionpocket in accordance with a further embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The deflection pocket in accordance with FIG. 1, which is formed of twomaterial layers 16 a, 16 b and the construction of which will beexplained in more detail in the following, can be secured together withthe airbag 12 via an annular holder element 22 by means of securingelements 32 in the form of screws at a non-illustrated base part of theairbag module in accordance with the invention. The lower layer 16 aforms the heat shield of the airbag module, which protects the airbag 12against the heat which arises during the triggering of a non-illustratedgas generator.

A region of the airbag 12, which bounds an inflow opening 14 and whichis also designated as the mouthpiece of the airbag 12, and a section ofthe lower material layer 16 a which bounds a flow-through opening 18 ofthis material layer 16 a are clamped at the airbag module by the holderring 22. The inflow opening 14 of the airbag 12 and the flow-throughopening 18 of the lower layer 16 a are thus defined by the holder ring22.

The lower layer 16 a and the upper layer 16 b of the deflection pocketwhich faces the vehicle interior in the vehicle are formed in each casecircularly with the same outer dimensions. The upper layer 16 b extendsover the flow-through opening 18 of the lower material layer 16 a, sothat the flow-through opening 18 is completely covered over by the upperlayer 16 b. Alternatively it is also possible to provide the upper layer16 b with e.g. small hole-like or slit-like openings in the region ofthe flow-through opening 18 of the lower layer 16 a, with the essentialpart of the flow-through opening 18 remaining covered over and the flowcross-section through these small openings in the upper layer 16 b beingsmall with respect to that of the flow-through opening 18 of the lowerlayer 16 a.

The upper layer 16 b extends over the holder ring 22 and is securedexclusively at connection locations formed by U-shaped seams 26 at thelower layer 16 a which will be described in more detail in the followingand is thus anchored at the airbag module via the lower layer 16 a.

The upper layer 16 b and the lower layer 16 a are connected to oneanother by four U-shaped seams 26 which are uniformly spaced in theperipheral direction. The free ends of the U-limbs lie at the edge ofthe material layers 16 a, 16 b, whereas the vertex of the U is arrangedat a small distance from the outer edge of the holder ring 22.

In this way a pocket for gas flow deflection with four radial gaspropagation paths 24 is formed by the two material layers 16 a, 16 b,which are sewn together, the shape of which is predetermined by thecourse of the seams 26 and which are in each case bounded by two U-limbsof two adjacent U-seams 26. In the exemplary embodiment in accordancewith FIG. 1 the radially outwardly widening gas propagation paths 24have in each case a trumpet-like shape. The interior of each U-seam 26forms an intermediate section 28 between two adjacent gas propagationpaths 24 which is not available for gas propagation.

Gas which is expelled by the gas generator of the airbag module can thusflow via the inflow opening 14 of the airbag 12 and the flow-throughopening 18 of the lower layer 16 a into the deflection pocket which isformed by the two material layers 16 a, 16 b in which it strikes againstthe region of the upper layer 16 b which covers over the flow-throughopening 18. The gas is thereby deflected and conducted into the radiallyextending gas propagation paths 24 so that it flows completely throughthe gas propagation paths 24 and out of the deflection pocket 16 a, 16 bin the radial direction into the airbag 12, as is indicated in FIG. 1 bythe large arrows.

In this way the airbag 12 is first inflated in the radial directionafter the gas generator is triggered, so that an impact surface withlarge radial dimensions is first created before the airbag 12 iscompletely inflated in the axial inflation direction.

The upper layer 16 b, which is applied to the heat shield of the airbagmodule which is formed by the lower layer 16 a, reinforces theprotective action of the heat shield and thus offers an additionalprotection for the airbag 12 against the heat which arises during thetriggering of the gas generator.

The embodiment in accordance with FIG. 2 differs from the embodiment ofFIG. 1 substantially through the number and the forming of the seams 26connecting the two material layers 16 a, 16 b of the deflection pocketto one another.

In accordance with FIG. 2 six straight double seams 26 which extend inthe radial direction are provided which in each case consist of twoparallel individual seams and form in this way a strip-like connectionlocation. The radially outer ends of the seams 26 lie at the edge of thetwo material layers 16 a, 16 b, whereas the radially inner ends of theseams 26 are in each case arranged at a small distance from the outeredge of the holder ring 22.

The seams 26 bound a total of six gas propagation paths 24 which widenoutwardly in the manner of a funnel, with two mutually diametricallyoppositely lying gas propagation paths 24 with relatively large openingangles being present, between which in each case a pair of adjacent gaspropagation paths 24 with a somewhat smaller opening angle is located.

Gas which is expelled by the gas generator and which flows into thedeflection pocket 16 a, 16 b is thus divided up over the six gaspropagation paths 24 and enters distributed over the entire periphery ofthe deflection pocket 16 a, 16 b from the deflection pocket 16 a, 16 bin the radial direction into the airbag 12.

Therefore after the triggering of the gas generator a radial deploymentof the airbag 12 again takes place first, before the latter iscompletely inflated in the axial direction.

In accordance with the invention the inflation behavior of the airbag 12can be intentionally set, through the number and the forming of theseams 26 which connect the material layers 16 a, 16 b to one another, insuch a manner that the airbag 12 optimally deploys first in the radialdirection in dependence on the respective conditions.

In this the gas propagation paths 24 can be intentionally configured independence on the position of the airbag module in the motor vehicleand/or on the configuration of possibly present flaps of a cover or capof the airbag module.

1. Airbag module for a motor vehicle comprising an inflatable airbaghaving an inflow opening, a deflection pocket disposed within theinflatable airbag, said deflection pocket comprising a first layerhaving a flow-through opening coextensive with the inflow opening, and asecond layer overlying the first layer and covering the inflow opening,said second layer having an edge coextensive with said first layer andbeing connected to the first layer by a plurality of substantiallyU-shaped seams having free ends at said edge and extending toward saidflow-through opening, said seams being spaced apart to form radial gaspropagation paths for allowing gas to flow from said inflow opening intothe airbag.
 2. Airbag module in accordance with claim 1, wherein thedeflection pocket is manufactured of at least two separate materiallayers.
 3. Airbag module in accordance with claim 1, wherein the firstlayer is formed by a material layer which is provided as a heat shieldfor the airbag.
 4. Airbag module in accordance with claim 1, furthercomprising a holder element formed in the shape of a ring, wherein theinflow opening of the airbag and the flow-through opening of the firstlayer are bounded by the holder element.
 5. Airbag module in accordancewith claim 1, wherein the deflection pocket is arranged substantiallycompletely within the airbag at least when the airbag is inflated. 6.Airbag module in accordance with claim 1, wherein the deflection pockethas multiple gas propagation paths uniformly distributed about theflow-through opening.
 7. Airbag module in accordance with claim 1,wherein the gas propagation paths have a trumpet-like shape.
 8. Airbagmodule in accordance with claim 1, wherein the first layer and thesecond layer have at least substantially the same outer dimensions. 9.Airbag module in accordance with claim 1, wherein the first layer andthe second layer are circular.